In a semiconductor integrated circuit in recent years, there has been a significant development of its micro-fabricated implementation and multi-layered implementation. Also, there has been a significant increase in the complication of its logic. Accordingly, a difficult situation is now underway in which it is extremely difficult to fabricate this semiconductor integrated circuit. As a result of this difficult situation, a defect that is caused to occur by the fabrication process tends to occur frequently. Consequently, it has become important to detect this defect efficiently and precisely, and to identify problems existing in the fabrication process.
The representative defect caused to occur by the fabrication process is a scum. The scum is a thin-film-like resist that remains at the foot portion of a resist pattern after the development process is over. If the scum is caused to occur, there arises a possibility that etching of the scum portion will not be performed, and that the resist pattern will be short-circuited. This possibility makes it required to inspect such factors as the scum's occurrence position and process-condition-based occurrence frequency.
In the case of detecting a defect generally, there exists the following method therefor: Namely, the comparison is made between the shape of a normal circuit pattern (which, hereinafter, will be referred to as “a reference pattern”) where no defect is caused to occur, and the shape of an inspection target's circuit pattern (which, hereinafter, will be referred to as “an inspection pattern”). Concretely, the operator selects an ideal-shape-equipped circuit pattern from among circuit patterns formed on wafers. Moreover, the operator photographs this ideal-shape-equipped circuit pattern, thereby creating the image of the reference pattern. Next, the operator photographs the inspection pattern, then performing superimposition between the inspection-pattern image and the reference-pattern image, and calculating a luminance difference between these images.
In PATENT LITERATURE 1, the disclosure has been made concerning a technology for detecting a defect by making the image comparison between the reference-pattern image and the inspection-pattern image. Here, the reference-pattern image is formed based on original design data.